1. Field of the Invention
This invention relates to a method of producing recording media having high recording density and high coercivity and its apparatus.
2. Discussion of the Background
In recent times, with increase of information quantity, request for recording media having high recording density has increased, and developments of magnetic recording media, optical recording media, magneto-optic recording media having magnetic thin film alloy by sputtering method continues.
Conventionally, in producing magnetic recording media by sputtering, chromium sublayer is formed on a substrate for recording media (hereinafter substrate), and a magnetic layer is formed on the sublayer by sputtering magnetic alloy such as Co-Ni-Cr. One sputtering method is called the stationary opposing type in which a disk-like target and a substrate are disposed with those centers aligned, and one method is called The passing by type or in-line type in which a magnetic film is sputtered on the substrate while a carrier arranged with many substrates passes between the targets.
In either production method, it is necessary to strictly control sputtering conditions such as temperature of the substrate or pressure, and it is important to produce them in a clean atmosphere, preventing contamination by impurities from the device or from jigs. Especially the detrimental influence of the impurity adhered to the jigs, is significant.
Conventionally, with respect to contamination, no consideration is particularly given. Accordingly since, during the sputtering of chromium sublayer, magnetic layer, and protection layer, the respective sputtering particles are adhered to the jigs, for instance, a carrier arranged with substrates, when these jigs are recycled, the sputtering particles adhered to the jig and the impurity adhered to these sputtering particles are separated into the atmosphere in the respective sputtering processes, and mixed into the magnetic recording media as impurities.
As mentioned above, the sputtered particles adhered to the carrier of substrates and the impurities adhered to the sputtered particles are detrimental to magnetic properties, and in particular, to the coercivity of the magnetic recording media.